To date, with respect to medical needles for puncturing a living body such as a human body, research has been made on configurations for reducing pain (luring puncturing. For example, the medical needle disclosed in Patent Literature 1 has ascending regions and descending regions whose cross-sectional areas increase or decrease with a predetermined regularity according to the distance from the tip. The frictional force between the needle and surrounding cells, which increases as the ascending region at the furthest tip penetrates a living body, is reduced due to the subsequent passage of the descending region, and it is thus possible to prevent damage to the surrounding cells and lessen pain.